System of motor control.



H. ALEXANDER.

SYSTEM OF-MOTOB CONTROL.

APPLIGATION FILED MAY 20, 1907.

901,514. Patented 001120, 1908.

2 SHEETS-SHEET 1.

Wit'nesses lrwenfior.

' Hans Alexander.

H. ALEXANDER.

SYSTEM OF MOTOR CONTROL.

APPLICATION II/LED MAY 20, 1907.

90 1 ,5 1 4;, Patented Oct. 20, 1908.

2 SHEETS-SHEET 2.

Fig. 3.

Witnesses lrwend'or.

, Hans Alexanda r:

. b gain UNITED STATES P TE OFFICE HANS ALEXANDER, OF BERLIN, GERMANY, ASSIGNOR To GENERAL ELECTRIC COMPANY,

- -'A coRPonA'rroN or NEW .YORK.

SYSTEM or moron coN'rnoL.

Patented Oct. 20, 1908.

Application filed May 20, 1907, Serial No. 374,674.

To all whom it may concern:

, "Be it known that I, HANS ALEXANDER, a sub ect of the King of Prussia, residing at.

Berlin, Germany, have invented certain new and useful Improvements in Systems of '.Motor Control, of which the-following is a specification.

' My invention relates to motor control systems, and more particularly to systems'of control of electrically driven rolling mill motors, or hke. motors, which are subject to he vy overloads and must be frequently reversed.

j starting torque is large.

, supplying the motor armature.

output of such generators. accomplished b Lmeans of a. differential. compounding fie d winding on the generator,

' motor.

'ihes stem most frequently used for roll; 1.

speed control of a direct-current motor with motors or the like comprises the or :by the use of a cumulative compound The use of series or compound motors has the further advantage that their When a motor havmg a field winding in series with the lineis used, it isnecessary to reversethe direction of current through this field winding with resgect to the armature upon every reversal of t e rolling mill, and when the machine is of 7 large size, a very heavy switch must be provided. I

It Is the object of my invention to avoid the use of such a switch. To this end I pro- 1 videan auxiliary field windingon the motor,

supplied with-current from fa'series-exciter driven by any suitable means but having its field windingin series with the line through wh ch the current flows supplyin the motor,

whereby the current flowing t rough the auxiliary field winding is proportional to the main line current. I

Other features of novelty which characterize my invention will be pointed out with articularity in the claims annexed to and orming a part'of this specification.

For a better understand of my invention, however, and other dvantages possessed-b it, reference may-be had to the following" escription taken in connection with the accompanying drawing in which Figure 1 shows'diagrammatically a. control This has beenits voltage,

system in accordance with my invention, in which a so arately excited generator supplies a motor aving main and auxiliary field windings, the auxiliary winding being cumulatively compoundin and excited by a series-exciter, the fielf of which is in series.

with the inotor armature; Fig. 2 shows a similar system in which a differentially compounding winding on the enerator is also supplied with current from t e series-exciter, and Fig. 3 shows a system similar to Fig. L-

except that an automatic cut-out in the main field circuit of'the, generator has its electromagnetic coil arranged in the armature circuit of the series-exciter.

In the figures of the drawing the armature, and a the fiel of 'the separately excited generator. This, generator may be the generator of a fly-wheel motorgenerator set. f

B represents a 'seperate exciter which may consist of any suita le source of current, for instance, of a small generator, as shown, sultably driven.

C represents the armature of the motor supplied with current from the armature A of the generator, and 0 represents the main field winding of the motor supplied with constant excitation from the exciter B.

Dis a series-exciter connected to the auxiliary field d of the motor C through a reversing switch E. The field winding .e of the series-exciter D is in series with the armatures A and C of the motor and generator.

F represents a control switch which is arranged to connect the generator field winding 0, to theexciter. B and to vary the current supplied to'the generator field winding.

G is a reversing switch connected between the field winding (1 of the generator and the exciter B so that the current through the field may be reversed.

Referring particularly to Fig. 1, with the circuit arrangement as shown, the armature of the generator A supplies current to the armature C of the motor, and the series-exciter D supplies current to the field winding (1 of. the motor in proportion to the current flowing in the main circuit. If this exciter is designed to work low on its saturation curve and consequentlythe current in the field winding (1 of the motor, will always bein'proportion to the current in the main circuit so that the fieldwinding (Z will'act as a cumulative compounding winding through A represents which the motor armature current flows.

By moving the handle of the regulator F so as to cut out more of the resistance of the rheostat, greater voltage is supplied to the winding a of the generator, and consequently the generator will operate at a greater voltage and will supply more current to the motor armature. When it is desired to reverse the motor C the handle of the rheostat is moved to the off position, which is at the extreme right, and thereversing switches E and G are thrown over. the armature current of the motor is re versed, while the motor field windings c and d are excited in the same direction as before Without the use of a switch in the armature circuit of the motor, but by means of a switch in the armature circuit of the exciter D, so that by building the machine D for a high voltage it is possible to reverse the compounding field winding of themotor, even where this motor is very large, by moving a comparatively li ht switch. In a large installation the series field winding, in case an.

ordinary series or compound wound motor is used, would have to be of verylarge dimencounteract the action of the field winding (1.

- This winding f is arranged to be supplied with current from the series-exciter D. The winding f does not need to be reversed upon the reversal of the direction of rotation of the motor Q, because upon the reversal of the field winding a the current flowing through the field winding e of the series-exciter is reversed thereby reversing the cur ent flowing from the armature D, since it rotates iii the same direction, and consequently, the current through the Winding f is also reversed with'the current through the winding a. In the system as illustrated in Fig. 2, upon a severe overload of the motor 0 the winding d tends to reduce the speed of the motor and the winding f of the generator tends to reduce the enerator voltage. The action of these two elds to ether tends to decrease the current supplie the motor 0 and consequently relieves the heavy overload on the generator.

Fig. 3 is similar to Fig. 1 except that an automatic cut-out I is in series with the exciter B and the field circuit a of the generator.- The-electromagnetic coil 9' of this cut-out is in series with the armature Dof the separate e'xciter'so that in case of a severe overload on the motor Q-thecurrent flowing through the exc ter armature'D being in proportion there- From this it will be seen that connection to, the coil 9 will be energized and will oper ate the cut-out I, thus opening the field circuit of the generator and stoppmgthe su ly ofcurrent to the motor armature O. lIus cut-out may operate to cut in a resistance in the field circuit a instead of opening the circuit completel By the use of a'cut-out, as shown in this 'gure, a great advantage is obtained because the coil of the cut-out is here arrangedto be actuated'by a very small cur rent. A similar cut-out may also be used in F with v the system as shown in fhile I have shown the field winding e of the series exciter D as being connected so that the entire current of the armatures A and C of the motor and generator flow therethrough, it is obvious that it might be so connected to the supply lines ofthe motor that instead of carrying the entire current it wouldcarry a current proportional to that in the supply lines, and I aim in the claims, hereto ap ended, to cover such a modification as we as any other modifications of my system that do not involve a departure from t e spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-'-

1. In combination, a separately excited generator supplying a motor, means for controllin the field strength of the generator to vary tie voltage supplied to sa1d motor, a separately excited field winding on said motor, a series-exciter connected to said field winding, and a field winding on said exciter in series with the supply lines of the motor.

2. In a system of control for reversible motors, a motor having a series field winding, a

variable voltage dynamo supplyin the motor, and a series-exciter havlng a ,eld winding connected in the main circuit, the series field winding of the motor being connected to the said exciter and being provided with a reversing switch.

3. In combination, a separately excited generator supplying a separately excited motor having -main and auxili means for controlling the field strength of t e generator to vary the voltage su plied to said motor, and an exciter connecte tov said auxiliary field winding and having afield winding in series with the supply lines of the motor.

4. In combination, a separately excited generator supplying a separately excited mo tor having main and auxiliary windin s,

means for controlling the field strength of t e generator to vary the voltage supplied to said motor, an a series exciter having a field windingv connected in the main circuit, the auxiliary fieldwinding of the motor bein connected to said-exciter and-being provide with a reversing switch.

5. In combination, a separately excited generator supplying a motor, meansfor con wmdin s,

. vary t trollin the field strengthof the generator to lie voltage supplied to. said motor, a separately excited field winding on said motor, and a series-exciter connected to said field winding and having a field, Windingin series with the supply lines of the motor, said exciter being so constructed and designed that the currentfiowing in said motor field winding is approximately,proportional to the current supplied the motor at all loads.

6. In combination, a separately excited generator having main and differentially compounding field windings, said generator field strength of said generator to vary the voltage suppliedthe motor, a field winding on said-motor, a series exciter connected to the-motor field winding and to said difierentially compounding. fieldwinding, and a field winding on said exciter in series with the supply lines of the motor.

generator havin generator havin 7. In combination, a separately excited generator having main and .diiierentially. com ounding fieldi windings, said generator supp ying a motor, means for 'controllingthe field strength of said generator to vary the\ voltage supplied the motor, a field winding on said motor, a series exciter having a field. winding connected in the main circuit, said exciter being connected to the differentially compounding field winding of the generator and to the field winding of the motor, and a reversing switch in the field winding circuit of the motor.- I

8. In combination a separateflky excited compounding fie d windings, said generator supp ying a sefiarately excited motor having main and aux iar field winding,'means forcontrolling the fie d strength of sad generator to vary the voltage supplied th motor, a series-exciter connected to said auxiliary field winding and to said generators' difierentially compounding field winding, and a field windin on said exciter in series with the supply hnes of the motor.

9.. In combination, a separately excited main and differentially com ounding fie d windings, said generator su fielii windings, means for controlling the \field strength of said generator to vary the voltage supplied the motor, an exciter connected to said auxiliary ,winding' and to said main and di erentially said motor having main an ying a motor having mainand auxiliary switches in-the main field. winding circuit of the generator and in the auxiliary field winding circuit of the motor.

' 10. In combination, a generator having a separately excited field supplying a motor,

means for controlling the field strength of the generator to vary the voltage supplied to said motor,'afield winding on said motor, a series exciter connected to said field winding of the motor and having a field winding inse- .ries with the supply line of the motor, and

an automatic cut-out having its actuating coil arranged in the field circuit of said motor. supplying a motor, means for controlling the 11. In combination, a generator having a separately excited field su lying a motor, means'for controlling the fie strength of the generator to vary the. voltage-supplied to 'said motor, a field winding on said motor, a

series-exciter connected to said field winding of the'motor and having a field winding in series with the supply lines of the motor, and an automatic cut-out having its actuating coil arranged'in the'field circuit of said motor, said cut-out bein arrangedto'act on the separately excited'fie d Ofjthe generator.

12. Incom-bination, agenerator having a separately excited field supplying a motor, said motor 1 having .main an windings, means forcontrolling the field strength of the generator to vary the voltage supplied to said motor, a series-exciter hav-' ing a field winding connectedin the main circult, the auxiliary field winding of the motor being connected to said exciter and being provided with a reversing switch, and an automatic cut-out having its-actuating coil arranged to be operated by a current supplied by said exciter.

13. In combinatioma generator having a separately excited field supplying a motor,

auxiliary field auxiliary field windin s, means for" controlling the field strengt of the generator to vary the voltage suppliedto said motor, an exciter connected to said auxiliary field winding .and having a field winding in series with the supply lines of the'motor, and an automaticv cut-out having its actuating coil arranged to be operated by the current supplied by said exciter, said 1 cut-out being arranged to act on the separately excited field ofthe generator.

. In witness whereof I have hereunto set my hand this 7th day of May, 1907. v

' HANS ALEXANDER.

Witnesses a -JULIUS RUMLAND,

FnnmNANnRoRB. 

